Peer-Reviewed, Published Research on the Adverse Effects of Mercury

248 Pages·2017·25.85 MB·English

Peer-Reviewed, Published Research
Showing Adverse Effects of Mercury
The literature showing the toxicity of mercury goes well beyond its associations
with autism. This document includes the abstracts for over 240 studies that show
the harmful effects of mercury, from both thimerosal and environmental sources,
on brain cells, immune cells and other body systems. These include cellular,
animal and human studies. There can be no justification for any intentional use
of mercury given the extent of this literature.
The following pages are abstracts from the peer reviewed 240+ studies.
childrenshealthdefense.org
Journal of Toxicology and Environmental Health, Part A, 70: 1046–1051, 2007
Copyright © Taylor & Francis Group, LLC
ISSN: 1528-7394 print / 1087-2620 online
DOI: 10.1080/15287390601172080
MUTeEH rcury, Lead, and Zinc in Baby Teeth of Children with
Autism Versus Controls
JamMercury, Leead, ands Zinc in BBaby Teeth. Adams and Jane Romdalvik
Chemical and Materials Engineering, Arizona State University, Tempe, Arizona
V. M. Sadagopa Ramanujam and Marvin S. Legator
Department of Preventive Medicine and Community Health, University of Texas Medical Branch,
Galveston, Texas, USA
including especially language/communication problems and
This study determined the level of mercury, lead, and zinc in social withdrawal. Therefore, they suggested that autism was
baby teeth of children with autism spectrum disorder (n = 15, age primarily due to infantile exposure to mercury. Their hypothe-
6.1 ± 2.2 yr) and typically developing children (n = 11, age = 7 ± sis is plausible because mercury exposure at hazardous levels
1.7 yr). Children with autism had significantly (2.1-fold) higher
is common in the United States and other countries; the Food
levels of mercury but similar levels of lead and similar levels of
and Drug Administration (FDA) estimates that 1 in 6 women in
zinc. Children with autism also had significantly higher usage of
oral antibiotics during their first 12 mo of life, and possibly higher the United States have mercury levels that increase the risk of
usage of oral antibiotics during their first 36 mo of life. Baby teeth neurological damage to their children. (Mahaffey et al., 2004)
are a good measure of cumulative exposure to toxic metals during The major sources of mercury exposure for infants are (1)
fetal development and early infancy, so this study suggests that
maternal seafood consumption, (2) maternal mercury amalgam
children with autism had a higher body burden of mercury dur-
dental fillings, and (3) thimerosal (an ethylmercury compound)
ing fetal/infant development. Antibiotic use is known to almost
completely inhibit excretion of mercury in rats due to alteration of in childhood vaccines and in anti-RhoD immune globulins
gut flora. Thus, higher use of oral antiobiotics in the children with given to Rh-negative mothers during pregnancy. Thimerosal
autism may have reduced their ability to excrete mercury, and was largely but not totally removed from childhood vaccines
hence may partially explain the higher level in baby teeth. Higher
by 2004.
usage of oral antibiotics in infancy may also partially explain the
Mercury toxicity might occur either due to high exposure,
high incidence of chronic gastrointestinal problems in individuals
with autism. or due to a decreased ability to excrete mercury, with the latter
case seeming to be the primary issue in autism. The primary
mechanism for excreting mercury involves its binding to glu-
tathione and then being excreted in the bile (Ballatori & Clarkson,
Autism is a severe developmental disorder that involves 1985). Infants are poor excretors because they produce less
social withdrawal, communication deficits, and stereotypic/ glutathione (Ballatori & Clarkson, 1984) and because they are
repetitive behaviors. The causes of autism are unknown, but usually on all-milk diets (which decreased mercury excretion
both genetic and environmental factors have been implicated. by a factor of 3 in a study of rats); thus, they are especially vul-
The purpose of this study was to investigate the environmental nerable to mercury poisoning (Rowland et al., 1984).
factor of heavy metals (mercury, lead) toxicity. Infants with autism were even more vulnerable to mercury
A thorough review by Bernard et al. (2001) reported that all toxicity, because their glutathione is much lower than in typi-
of the major symptoms reported in the literature for autism cal children (James et al., 2004; Audhya, 2004) and a higher
were also reported for cases of infantile mercury poisoning, fraction of their glutathione is oxidized (James et al., 2004).
Further, two studies (Konstantareas & Homatidis, 1987;
Adams et al., 2003) found that children with autism had much
Received 19 June 2006; accepted 13 November 2006. higher usage of oral antibiotics, which (in rats) resulted in a
We thank the Autism Research Institute, directed by Bernard near-total loss of the ability to excrete mercury (Rowland et al.,
Rimland, PhD, for funding this research. We thank the children and
1980, 1984). The reason appears to be that normal gut anaer-
their families for participating. We thank Vas Aposhian, Jon
obes are able to convert methylmercury (which is rapidly
Pangborn, and Boyd Haley for helpful comments.
Address correspondence to James B. Adams, Arizona State absorbed) into inorganic mercury (which is poorly absorbed
University, PO Box 876006, USA. E-mail: [email protected] and hence mostly excreted). In contrast, most strains of yeast
1046
HindawiPublishingCorporation
JournalofToxicology
Volume2009,ArticleID532640,7pages
doi:10.1155/2009/532640
Research Article
The Severity of Autism Is Associated with Toxic Metal Body
Burden and Red Blood Cell Glutathione Levels
J.B.Adams,1M.Baral,2E.Geis,3J.Mitchell,1J.Ingram,3A.Hensley,3I.Zappia,3S.Newmark,4
E.Gehn,3R.A.Rubin,5K.Mitchell,3J.Bradstreet,2,6andJ.M.El-Dahr7
1DivisionofBasicMedicalSciences,SouthwestCollegeofNaturopathicMedicine,Tempe,AZ85282,USA
2DepartmentofPediatricMedicine,SouthwestCollegeofNaturopathicMedicine,Tempe,AZ85282,USA
3AutismResearchInstitute,SanDiego,CA92116-2599,USA
4CenterforIntegrativePediatricMedicine,Tucson,AZ85711,USA
5DepartmentofMathematics,WhittierCollege,Whittier,CA90601-4413,USA
6InternationalChildDevelopmentResourceCenter,Phoenix,AZ,USA
7DepartmentofPediatrics,TulaneUniversitySchoolofMedicine,NewOrleans,LA70112,USA
CorrespondenceshouldbeaddressedtoJ.B.Adams,[email protected]
Received10April2009;Revised30June2009;Accepted12July2009
RecommendedbyWeiZheng
This study investigated the relationship of children’s autism symptoms with their toxic metal body burden and red blood cell
(RBC) glutathione levels. In children ages 3–8 years, the severity of autism was assessed using four tools: ADOS, PDD-BI,
ATEC, and SAS. Toxic metal body burden was assessed by measuring urinary excretion of toxic metals, both before and after
oraldimercaptosuccinicacid(DMSA).Multiplepositivecorrelationswerefoundbetweentheseverityofautismandtheurinary
excretionoftoxicmetals.Variationsintheseverityofautismmeasurementscouldbeexplained,inpart,byregressionanalysesof
urinaryexcretionoftoxicmetalsbeforeandafterDMSAandthelevelofRBCglutathione(adjustedR2of0.22–0.45,P <.005in
allcases).Thisstudydemonstratesasignificantpositiveassociationbetweentheseverityofautismandtherelativebodyburdenof
toxicmetals.
Copyright©2009J.B.Adamsetal.ThisisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense,
whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
1.Background of autism. A small study by Adams et al. [4] found that
childrenwithautismhada2-timehigherlevelofmercuryin
Autism is a severe developmental disorder which involves theirbabyteeththantypicalchildren.AstudybyBradstreet
social withdrawal, communication deficits, and stereo- et al. [5] investigated the body burden of toxic metals by
typic/repetitivebehaviour.Thepathophysiologicaletiologies giving dimercaptosuccinic acid (DMSA), an oral chelation
whichprecipitateautismsymptomsremainelusiveandcon- medication approved by the FDA for treating infantile lead
troversialinmanycases,butbothgeneticandenvironmental poisoning.Theyfoundthatthechildrenwithautismexcreted
factors (and their interactions) have been implicated. One 3.1timesasmuchmercuryintotheirurine(whichiswhere
environmental factor that has received significant attention DMSA is excreted), P < .0002, but lead and cadmium
isthebodyburdenofmercury,lead,andothertoxicmetals levels were not significantly different. Overall there is some
[1–5]. evidence to suggest that mercury and possibly other toxic
Bernardetal.[1]discussedthemanysimilaritiesbetween metalsarerelatedtotheetiologyofautism.
thesymptomsofchildrenwithautismandchildrenpoisoned This study investigates the possible relationship of the
by mercury. An epidemiology study by Windham et al. [2] severity of autism to the relative body burden of toxic
foundthattheamountofairbornepollutants,andespecially metals.Theseverityofautismwasassessedusingfourtools,
mercury, correlated with an increased risk for autism. A a professional evaluation based on the Autism Diagnostic
study by DeSoto and Hitlan [3] found that blood levels ObservationSchedule[6],andparentalevaluationsbasedon
of mercury did significantly correlate with the diagnosis thePervasiveDevelopmentalDisordersBehaviourInventory
BiolTraceElemRes(2013)151:171–180
DOI10.1007/s12011-012-9551-1
Toxicological Status of Children with Autism vs. Neurotypical
Children and the Association with Autism Severity
JamesB.Adams&TapanAudhya&SharonMcDonough-Means&
RobertA. Rubin& David Quig&Elizabeth Geis&Eva Gehn&
Melissa Loresto& Jessica Mitchell&SharonAtwood&
Suzanne Barnhouse&Wondra Lee
Received:3August2012/Accepted:12November2012/Publishedonline:29November2012
#SpringerScience+BusinessMediaNewYork2012
Abstract This study investigates both the level of toxic significant variables. Overall, children with autism have
metals in children with autism and the possible association higher average levels of several toxic metals, and levels of
of those toxic metals with autism severity. This study in- several toxic metals are strongly associated with variations
volved55childrenwithautismages5–16yearscomparedto in the severity of autism for all three of the autism severity
44controlswithsimilarageandgender.Thestudyincluded scalesinvestigated.
measurements of toxic metals in whole blood, red blood
cells(RBC), andurine. Theautismgroup hadhigher levels Keywords Autism .Toxicmetals .Mercury.Lead .
ofleadinRBC(+41%,p00.002)andhigherurinarylevels Thallium .Tungsten
of lead (+74 %, p00.02), thallium (+77 %, p00.0001), tin
(+115 %, p00.01), and tungsten (+44 %, p00.00005).
However, the autism group had slightly lower levels of Backgroundand Significance
cadmium in whole blood (−19 %, p00.003). A stepwise,
multiple linear regression analysis found a strong associa- Determination of toxic metal exposure in classic lead poi-
tionoflevelsoftoxicmetalswithvariationinthedegreeof soning, such as due to ingestion of lead paint, is relatively
severity of autism for all the severity scales (adjusted R2 of easyandinvolvesmeasuringbloodlevelsoflead.However,
0.38–0.47,p<0.0003).Cadmium(wholeblood)andmercu- inautism,theproblemappearstousuallynotbehighexpo-
ry (whole blood and RBC) were the most consistently sure, but rather decreased excretion. The half-life of lead,
mercury, and other toxic metals in the blood is weeks to
months, so those metals rapidly leave the blood and accu-
: : : : :
J.B.Adams(*: ) E.Geis E.Gehn M.Loresto S.Atwood mulateintissueand/orbone.Sincebiopsiesofthosetissues
S.Barnhouse W.Lee
areinvasive,thismakesassessmentoftoxicmetalexposure
ArizonaStateUniversity,POBox876106,
inautism more complex.
Tempe85287-6006AZ,USA
e-mail:[email protected] Many studies suggest that children with autism have a
decreasedabilitytoexcretetoxicmetals,leadingtoahigher
T.Audhya
bodyburden.Thedecreasedabilitytoexcretetoxicmetalsis
HealthDiagnostics,SouthAmboy,NJ,USA
partlyduetolowglutathione[1–4]sinceglutathioneconju-
S.McDonough-Means gation(andsubsequentexcretioninthefeces)istheprimary
IntegrativeDevelopmentalPediatrics,Tucson,AZ,USA pathway for removal of some toxic metals. Another factor
thatalsodecreasesabilitytoexcretetoxicmetalsinfecesis
R.A.Rubin
increased use of oral antibiotics [5–8] since oral antibiotics
DepartmentofMathematics,WhittierCollege,Whittier,CA,USA
have been shown (in rats) to almost completely inhibit
D.Quig excretion of mercury [9, 10] due to their effect on altering
Doctor’sData,St.Charles,IL,USA
gut flora. This is consistent with two studies which found
lower levels of mercury in the baby hair of children with
J.Mitchell
SouthwestCollegeofNaturopathicMedicine,Tempe,AZ,USA autism, [8, 11], one study which found decreased lead,
RESEARCHARTICLE
Significant Association of Urinary Toxic Metals
and Autism-Related Symptoms—A Nonlinear
Statistical Analysis with Cross Validation
JamesAdams1*,DanielP.Howsmon2,UweKruger2,ElizabethGeis1,EvaGehn1,
ValeriaFimbres1,ElenaPollard1,JessicaMitchell3,JulieIngram1,RobertHellmers4,
DavidQuig5,JuergenHahn2
1ArizonaStateUniversity,Tempe,AZ,UnitedStatesofAmerica,2RensselaerPolytechnicInstitute,Troy,
NY,UnitedStatesofAmerica,3SouthwestCollegeofNaturopathicMedicine,Tempe,AZ,UnitedStatesof
a1111111111
America,4ArizonaAllergyAssociates,Phoenix,AZ,UnitedStatesofAmerica,5Doctor’sData,St.Charles,
a1111111111
IL,UnitedStatesofAmerica
a1111111111
a1111111111 *[email protected]
a1111111111
Abstract
OPENACCESS
Introduction
Citation:AdamsJ,HowsmonDP,KrugerU,Geis
Anumberofpreviousstudiesexaminedapossibleassociationoftoxicmetalsandautism,
E,GehnE,FimbresV,etal.(2017)Significant
AssociationofUrinaryToxicMetalsandAutism- andoverhalfofthosestudiessuggestthattoxicmetallevelsaredifferentinindividualswith
RelatedSymptoms—ANonlinearStatistical AutismSpectrumDisorders(ASD).Additionally,severalstudiesfoundthatthoselevelscor-
AnalysiswithCrossValidation.PLoSONE12(1):
relatewiththeseverityofASD.
e0169526.doi:10.1371/journal.pone.0169526
Editor:FranciscoJ.Esteban,UniversidaddeJaen,
Methods
SPAIN
Inordertofurtherinvestigatethesepoints,thispaperperformsthemostdetailedstatistical
Received:March25,2016
analysistodateofadatasetinthisfield.Firstmorningurinesampleswerecollectedfrom67
Accepted:November16,2016
childrenandadultswithASDand50neurotypicalcontrolsofsimilarageandgender.The
Published:January9,2017
sampleswereanalyzedtodeterminethelevelsof10urinarytoxicmetals(UTM).Autism-
Copyright:©2017Adamsetal.Thisisanopen relatedsymptomswereassessedwithelevenbehavioralmeasures.Statisticalanalysiswas
accessarticledistributedunderthetermsofthe
usedtodistinguishparticipantsontheASDspectrumandneurotypicalparticipantsbased
CreativeCommonsAttributionLicense,which
upontheUTMdataalone.Theanalysisalsoincludedexaminingtheassociationofautism
permitsunrestricteduse,distribution,and
reproductioninanymedium,providedtheoriginal severitywithtoxicmetalexcretiondatausinglinearandnonlinearanalysis.“Leave-one-out”
authorandsourcearecredited. cross-validationwasusedtoensurestatisticalindependenceofresults.
DataAvailabilityStatement:Allrelevantdataare
withinthepaperanditsSupportingInformation ResultsandDiscussion
files.
Averageexcretionlevelsofseveraltoxicmetals(lead,tin,thallium,antimony)weresignifi-
Funding:TheASUportionofthisstudywasfunded
cantlyhigherintheASDgroup.However,ASDclassificationusingunivariatestatistics
byagiftfromtheAutismResearchInstitute(ARI),
www.autism.com.Thefundershadnoroleinstudy proveddifficultduetolargevariability,butnonlinearmultivariatestatisticalanalysissignifi-
design,datacollectionandanalysis,decisionto cantlyimprovedASDclassificationwithTypeI/IIerrorsof15%and18%,respectively.
publish,orpreparationofthemanuscript.TheRPI
Theseresultsclearlyindicatethattheurinarytoxicmetalexcretionprofilesofparticipantsin
portionofthestudywasnotfunded.DavidQuig
theASDgroupweresignificantlydifferentfromthoseoftheneurotypicalparticipants.Simi-
andRobertHellmersareemployeesofDoctors
DataandArizonaAllergyAssociates,respectively, larly,nonlinearmethodsdeterminedasignificantlystrongerassociationbetweenthe
PLOSONE|DOI:10.1371/journal.pone.0169526 January9,2017 1/24
Thimerosal induces TH2 responses via influencing cytokine
secretion by human dendritic cells
Anshu Agrawal,1 Poonam Kaushal, Sudhanshu Agrawal, Sastry Gollapudi, and Sudhir Gupta
Division of Basic and Clinical Immunology, University of California, Irvine, California, USA
Abstract: Thimerosalisanorganicmercurycom- associationbetweentheexposuretomercury(viavaccination)and
poundthatisusedasapreservativeinvaccinesand thedevelopmentofneurodevelopmentaldisorders,especiallyau-
pharmaceutical products. Recent studies have tism and learning disabilities [3–8]. This has led to thimerosal
shown a TH2-skewing effect of mercury, although being withdrawn from pediatric vaccines in the United States
the underlying mechanisms have not been identi- starting in 1999 (Centers for Disease Control and Prevention,
fied. In this study, we investigated whether thimer- 1999). Nevertheless, thimerosal is still used in influenza, diph-
osal can exercise a TH2-promoting effect through theriatoxoidandacellularpertussis,andtetanustoxoidvaccines.
modulation of functions of dendritic cells (DC). Themajorityofthestudiesaredirectedtowardunderstandingthe
Thimerosal, in a concentration-dependent man- neurotoxiceffectofthimerosal,andfewstudiesdealwithitseffect
ner, inhibited the secretion of LPS-induced proin- ontheimmunesystem.
flammatory cytokines TNF-(cid:1), IL-6, and IL-12p70 The effect of mercury on the immune system has been
from human monocyte-derived DC. However, the studied mostly in rodents. These studies have revealed that
secretionofIL-10fromDCwasnotaffected.These subtoxic doses of mercury exposure in genetically susceptible
thimerosal-exposed DC induced increased TH2
H-2 mice strains result in the development of systemic auto-
(IL-5 and IL-13) and decreased TH1 (IFN-(cid:2)) cyto-
immunitycharacterizedbylymphoproliferationwithpolyclonal
kine secretion from the T cells in the absence of B cell activation and hyper-(cid:1)-globulinemia, production of au-
additional thimerosal added to the coculture.
toantibodies targeting the 34-kDa nucleolar protein fibrillarin,
Thimerosal exposure of DC led to the depletion of
and development of immune-complex deposits [9–15]. The
intracellular glutathione (GSH), and addition of
different forms of mercury differ in the type and range of
exogenous GSH to DC abolished the TH2-promot-
immune disorders, and ethylmercury (thimerosal) and inor-
ing effect of thimerosal-treated DC, restoring se-
ganic mercury are similar in that they cause systemic autoim-
cretion of TNF-(cid:1), IL-6, and IL-12p70 by DC and
munity, characterized by a marked increase of IgE and sys-
IFN-(cid:2) secretion by T cells. These data suggest that
temic immune-complex deposits [16, 17]. Antifibrillarin auto-
modulation of TH2 responses by mercury and
antibodies (AFA) and maximum levels of serum IgE are
thimerosal, in particular, is through depletion of
present as early as 10 days after exposure to ethylmercury in
GSHinDC. J.Leukoc.Biol.81:474–482;2007.
the mice [16]. Similar to the autoimmune disease induced by
inorganic mercury, thimerosal induces a distinctly increased
Key Words: APC (cid:1) heavy metal (cid:1) immune modulation
expressionofIL-4mRNAandalargeincreaseinTH2-depen-
dent, Ig-secreting cells and serum Igs [18]. The increase in
IL-4 has been attributed to a direct induction of IL-4 gene
INTRODUCTION
expression in lymphocytes by mercury [19]. Methylmercury,
conversely,inducesonlymodesttitersofAFAandnoneofthe
Exposure to mercury is widespread in the world, and inorganic abovesymptoms[16,17,20].Oneofthepossibleexplanations
mercury, ethylmercury, and methylmercury are the predominant is that ethylmercury is converted much faster into inorganic
chemicalspecies.Theprimarysourcesofexposuretomercuryare mercury compared with methylmercury, leading to an earlier
amalgam,mercuryvapors,vaccination,andseafoodconsumption and more potent effect on the immune system. The immuno-
[1–3]. Thimerosal (ethylmercurithiosalicylate) is an organic mer- suppressiveeffectsofethylandmethylmercuryaresimilarand
curycompoundthathasbeenusedasapreservativeinvaccines, more potent than inorganic mercury in that they both cause
intramuscular immune globulin preparations, skin test antigens, reductioninthenumberandproliferativecapacityofsplenicT
antivenoms,ophthalmicandnasalproducts,andtattooinks[1–3].
and B lymphocytes [17, 20]. Studies in humans document
Ithas49.6%mercurybyweight,andfollowingitsadministration,
its metabolite, ethylmercury, dissociates from thiosalicylic acid
andbindstobloodorothertissue.Theextensiveuseofvaccines
intoday’ssocietyhasledtoconcernsaboutimmunizationsafety. 1Correspondence:DivisionofBasicandClinicalImmunology,Med.Sci
Today,childrenreceivemoretotalnumberofvaccinationsgiven I C-240, University of California, Irvine, CA 92697, USA. E-mail:
[email protected]
together during the first two years of life, leading to exposure to
Received July 21, 2006; revised August 22, 2006; accepted October 6,
quantities of mercury that exceeds the safety guidelines through
2006.
thimerosal in vaccines. There is an increasing concern about doi:10.1189/jlb.0706467
474 JournalofLeukocyteBiology Volume81,February2007 0741-5400/07/0081-474©SocietyforLeukocyteBiology
Downloaded from www.jleukbio.org to IP 69.12.21.180. Journal of Leukocyte Biology Vol.81, No.2 , pp:474-482, October, 2016
International Journal of
Environmental Research
and Public Health
Review
Genetic Aspects of Susceptibility to Mercury Toxicity:
An Overview
VirginiaAndreoli*andFrancescaSprovieri
InstituteofAtmosphericPollutionResearch,NationalResearchCouncilofItaly,DivisionofRende,
Rende87036,Italy;[email protected]
* Correspondence:[email protected];Tel.:[phone]
AcademicEditor:PaulB.Tchounwou
Received:3November2016;Accepted:12January2017;Published:18January2017
Abstract: Humanexposuretomercuryisstillamajorpublichealthconcern. Inthiscontext,children
haveahighersusceptibilitytoadverseneurologicalmercuryeffects,comparedtoadultswithsimilar
exposures. Moreover,thereexistsamarkedvariabilityofpersonalresponsetodetrimentalmercury
action,inparticularamongpopulationgroupswithsignificantmercuryexposure. Newscientific
evidenceongeneticbackgroundshasraisedtheissueofwhethercandidatesusceptibilitygenescan
makecertainindividualsmoreorlessvulnerabletomercurytoxicity. Inthisreview,theaimisto
evaluateanewgeneticdimensionanditsinvolvementinmercuryriskassessment,focusingonthe
importantroleplayedbyrelevantpolymorphisms, locatedinattractivegenetargetsformercury
toxicity. Existingoriginalarticlesonepidemiologicresearchwhichreportadirectlinkbetweenthe
geneticbasisofpersonalvulnerabilityanddifferentmercuryrepercussionsonhumanhealthwillbe
reviewed. Basedonthisevidence,acarefulevaluationofthesignificantmarkersofsusceptibilitywill
besuggested,inordertoobtainapowerfulpositive“feedback”toimprovethequalityoflife. Large
consortiaofstudieswithclearphenotypicassessmentswillhelpclarifythe“windowofsusceptibility”
inthehumanhealthrisksduetomercuryexposure.
Keywords:mercury;toxicokinetics;humanhealth;riskassessment;childrenexposure;environmental
genetics;DNAvariants;biomarkersofsusceptibility
1. Introduction
Mercury(Hg)isaglobalpollutantandwell-knownneurotoxinthathasraisedgreatfearinthe
internationalscientificcommunity, duetoavarietyofsignificantanddocumentedadverseeffects
onhumanhealthandtheenvironmentthroughouttheworld[1]. Despitebeingawell-documented
systemictoxicant,anunderstandingofallthemolecularmechanismsunderlyingthedamageinduced
byHgisstillelusive.
TheneedtofurtherreduceHgemissions,aswellastodeveloppreventivestrategiesinrelation
toHgriskassessmentandmanagementmakesthesituationevenmorechallenging,especiallyfor
thoseindividualsmostsusceptibletotheeffectsofHgexposure,suchaschildrenandadolescents[1].
ThetwocategoriesarehighlysensitivetotheneurotoxicHgeffects,displayingextremevariabilityin
mainlyneurologicalandneurobehaviouraloutcomesthroughoutsubsequentlifestages[2].
ThepathologicalimpactofHgonhumansandotherorganismsiswidelyproven,andtheoverall
pictureisquitecomplex. Humanexposuremayoccurchronicallythroughavarietyofpathwaysinthe
worldpopulation,includingindustrialprocesses,occupationalandhouseholduses,dentalamalgams,
Hg-containingvaccines,consumptionofcontaminatedfishandmarinemammals,andmanyothers[2].
To date, two main types of risk for human health have been detected: a direct one, related to the
inhalation ofgaseous Hg, with several pathophysiologicalimpacts, andcollateral risks, related to
differencesbetweenHgspecies.
Int.J.Environ.Res.PublicHealth2017,14,93;doi:10.3390/ijerph14010093 www.mdpi.com/journal/ijerph
Journal of Toxicology and Environmental Health, Part A, 71: 1349–1351, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1528-7394 print / 1087-2620 online
DOI: 10.1080/15287390802271723
AnUTEH Investigation of Porphyrinuria in Australian Children
with Autism
DaPorvphyrinuiria idn Austra lianW Children with .Aut ismAustin and Kerrie Shandley
Swinburne Autism Bio-Research Initiative (SABRI), Faculty of Life and Social Sciences, Swinburne
University of Technology, Melbourne, Australia
Mutter et al., 2005; Kern & Jones, 2006). Urinary porphyrins
Two recent studies, from France (Nataf et al., 2006) and the provide a convenient and non-invasive measure of xenobiotic
United States (Geier & Geier, 2007), identified atypical urinary exposure generally (Brewster, 1988) and of Hg specifically
porphyrin profiles in children with an autism spectrum disorder (Woods et al., 2005; Heyer et al., 2006).
(ASD). These profiles serve as an indirect measure of environ-
Excess urinary porphyrin excretion (porphyrinuria) results
mental toxicity generally, and mercury (Hg) toxicity specifically,
from the inhibition of enzymatic steps in conditions including
with the latter being a variable proposed as a causal mechanism of
ASD (Bernard et al., 2001; Mutter et al., 2005). To examine genetic deficiencies in heme production enzymes, hepatitis,
whether this phenomenon occurred in a sample of Australian renal disease, and erythroid disease (Gross et al., 2000), as well
children with ASD, an analysis of urinary porphyrin profiles was as by heavy metal inhibition (Bowers et al., 1992; Woods,
conducted. A consistent trend in abnormal porphyrin levels was
1996). The causal relationship between Hg and porphyrinuria
evidenced when data was compared with those previously
has been demonstrated both in rats (Pingree et al., 2001) and in
reported in the literature. The results are suggestive of environmen-
tal toxic exposure impairing heme synthesis. Three independent humans (Woods et al., 1993).
studies from three continents have now demonstrated that por- The steps in the heme pathway most vulnerable to heavy metal
phyrinuria is concomitant with ASD, and that Hg may be a likely inhibition are those that involve uroporphyrin decarboxylase
xenobiotic to produce porphyrin profiles of this nature.
(Woods & Kardish, 1983) and coproporphyrinogen oxidase
(Woods et al., 2005). The result of these inhibitions is specific
elevations of urinary coproporphyrin and pentacarboxyporphyrin
levels. Although nonmetal agents targeting the heme pathway
Autism is a neurodevelopmental disorder presenting in child-
also elevate urinary porphyrin levels (Daniell et al., 1997),
hood that affects up to 1 in 150 children in the United States
precoproporphyrin (also known as keto-isocoproporphyrin) is
(Centers for Disease Control, 2006) and 1 in 160 in Australia
produced by in vivo conversion of pentacarboxyporphyrin in the
(Wray & Williams, 2007). Autism is characterized by severe
presence of heavy metal, providing a specific porphyrin marker
impairments in socialization, communication, and behavior
for Hg exposure (Woods et al., 2005; Heyer et al., 2006).
(American Psychiatric Association, 1994). The prevalence of
Two previous studies reported porphyrinuria among autistic
autism is increasing at epidemic rates (Yazbak, 2003) that can-
subjects consistent with elevated body burden of Hg (Nataf
not be accounted for by changing diagnostic criteria or improved
etal., 2006; Geier & Geier, 2007). The pattern is one of gener-
diagnostic systems (Blaxill et al., 2003; Croen et al., 2002).
alized porphyrinuria with marked elevation of coproporphyrin
Mercury (Hg) toxicity has been proposed as a causal
and of precoproporphyrin and of the ratio of coproporphyrin/
mechanism whereby a small subset of children are uniquely
uroporphyrin. This study aimed to examine this phenomenon
sensitive to Hg and, in such individuals, exposure triggers a
among a group of Australian autistic children.
cascade of events leading to autism (Bernard et al., 2001;
METHODS
We are indebted to Dr. Richard Lathe (Pieta Research, Edinburgh,
UK) and Dr. Elisabeth Minder (Swiss Porphyrin Reference Subjects
Laboratory SGKC/IFCC, Stadtspital Triemli, Zürich, Switzerland) for Urinary porphyrin profiles were obtained from 41 consecu-
providing their original data for reanalysis.
tive patients with an ASD presenting to the first author’s
Address correspondence to Dr. David W. Austin, PhD, Faculty
psychology clinic from October 2006 through March 2008.
of Life and Social Sciences, Swinburne University of Technology,
Mail 31, PO Box 218, Hawthorn VIC 3122, Australia. E-mail: Each patient was previously diagnosed with an ASD, by a
[email protected] health professional, based upon accepted international
1349
Thimerosal Exposure in Early Life and Neuropsychological
Outcomes 7–10 Years Later
John P. Barile,1 PHD, Gabriel P. Kuperminc,1 PHD, Eric S. Weintraub,2 MPH, Jonathan W. Mink,3 MD,
and William W. Thompson,4 PHD
1DepartmentofPsychology,GeorgiaStateUniversity,2Immunization SafetyOffice, USCenters forDisease
ControlandPrevention, 3UniversityofRochesterMedical Center,and 4Division ofAdultandCommunity
Health,National Center forChronicDiseasePreventionandHealth Promotion,US CentersforDiseaseControl
andPrevention
All correspondence concerning this article should be addressed to John P. Barile, PhD, Division of Adult and
Community Health, National Center for Chronic Disease Prevention and Health Promotion, US Centers for
Disease Control and Prevention, 4770 Buford Highway, NE, Mailstop K51, Atlanta, GA, 30331-3717, USA.
E-mail: [email protected]
D
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Received December 6, 2010; revisions received June 8, 2011; accepted June 9, 2011 w
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Objective The authors used a public use data set to investigate associations between the receipt of fro
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thimerosal-containing vaccines and immune globulins early in life and neuropsychological outcomes h
ttp
assessed at 7–10 years. Methods The data were originally created by evaluating 1,047 children ages 7–10 ://jp
years and their biological mothers. This study developed seven latent neuropsychological factors and ep
s
y
regressed them on a comprehensive set of covariates and thimerosal exposure variables. Results The .o
x
authors found no statistically significant associations between thimerosal exposure from vaccines early in life ford
jo
and six of the seven latent constructs. There was a small, but statistically significant association between u
rn
early thimerosal exposure and the presence of tics in boys. Conclusions This finding should be inter- als
.o
preted with caution due to limitations in the measurement of tics and the limited biological plausibility rg
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regarding a causal relationship. y g
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Key words children; modeling; neuropsychology; public health; structural equation. t o
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Introduction associations between methylmercury exposure and neuro- r 1, 2
0
psychologicaloutcomes(Crump,Kjellstrom,Shipp,Silvers, 1
Theassociationbetweenexposuretothimerosal-containing 6
& Stewart, 1998; Grandjean et al., 1999). Specifically, the
vaccines and developmental outcomes has been debated
Faroe Island studies found that high levels of methylmer-
since 1999 (Bernard, 2008; Clements, Ball, Ball, & Pratt,
cury exposure due to maternal consumption of mercury-
2001; Offit, 2007; Rooney, 2008; Sugarman, 2007) when
contaminated fish during pregnancy have been associated
the Food and Drug Administration (FDA) determined
with children exhibiting lower motor function and verbal
that children who received multiple thimerosal containing
skills at 7 years of age (Grandjean et al., 1999). As a pre-
vaccines at a young age were at risk for exceeding the
cautionary measure, the U.S. Public HealthService recom-
Environmental Protection Agency’s (EPA) safety limits for
mended the removal of thimerosal from vaccines
methylmercury (Ball, Ball, & Pratt, 2001; Stratton, Gable,
administered to children early in life and the Centers for
& McCormick, 2001). EPA had never determined safety
limitsforethylmercuty,thecompoundfoundinthimerosal Disease Control and Prevention (CDC) proceeded to
containingvaccines.EPAsmethylmercurysafteylimitshad sponsor several studies investigating the possible associa-
been determined based on previous studies that found tions between exposure to thimerosal-containing vaccines
JournalofPediatricPsychology37(1)pp.106–118,2012
doi:10.1093/jpepsy/jsr048
AdvanceAccesspublicationJuly23,2011
JournalofPediatricPsychologyvol.37no.1!TheAuthor2011.PublishedbyOxfordUniversityPressonbehalfoftheSocietyofPediatricPsychology.
Allrightsreserved.Forpermissions,pleasee-mail:[email protected].
TOXICOLOGICALSCIENCES74,361–368(2003)
DOI:10.1093/toxsci/kfg126
Thimerosal Induces DNA Breaks, Caspase-3 Activation, Membrane
Damage, and Cell Death in Cultured Human Neurons and Fibroblasts
David S. Baskin,1 Hop Ngo, and Vladimir V. Didenko
DepartmentofNeurosurgery,BaylorCollegeofMedicine,6560FanninSuite944,Houston,Texas77030;andVeteransAffairsMedicalCenter,
Houston,Texas77030
ReceivedFebruary10,2003;acceptedApril18,2003
ranging from 0.003 to 0.01% (30–100 (cid:1)g/ml) (Ball et al.,
Thimerosalisanorganicmercurialcompoundusedasapreser- 2001). Thimerosal contains 49.6 % mercury by weight and
vativeinbiomedicalpreparations.Littleisknownaboutthereac-
releases ethylmercury as a metabolite. In the body, ethylmer-
tionsofhumanneuronalandskincellstoitsmicro-andnanomo- cury can be converted to inorganic mercury, which then pref- Do
lar concentrations, which can occur after using thimerosal- w
erentially accumulates in the kidneys and brain (Blair et al., n
containing products. A useful combination of fluorescent lo
techniquesfortheassessmentofthimerosaltoxicityisintroduced. 1975). Inorganic mercury is known to induce membrane and ade
Scehroerbtr-atelrcmortthicimalenroesuarlotnosxiacnitdyiwnansoinrmveasltihgautmedaninficburlotubrlaesdtsh.uCmeallns DinNcAelldacmulatugree(cFoenrrdaittieotnasl.i,t2w0a0s2;shBoewn-nOtzoerbeetmalu.,ta2g0e0n0i)c, aanndd d from
wereincubatedwith125-nMto250-(cid:1)Mconcentrationsofthimer- generateDNAbreaksinconcentrationsbelow500nM(Schurz http
osal for 45 min to 24 h. A 4(cid:1), 6-diamidino-2-phenylindole dihy- et al., 2000). Ethylmercury can significantly increase the con- ://to
drochloride (DAPI) dye exclusion test was used to identify non- centrationofinorganicmercuryinmanyorgans(Magosetal., xs
c
viable cells and terminal transferase-based nick-end labeling 1985). After in vivo administration, ethylmercury passes i.o
x
(TUNEL)tolabelDNAdamage.Detectionofactivecaspase-3was through cellular membranes and concentrates in cells in vital fo
performed in live cell cultures using a cell-permeable fluorescent organs, including the brain, where it releases inorganic mer- rdjo
caspaseinhibitor.Themorphologyoffluorescentlylabelednuclei cury,raisingitsconcentrationshigherthanequimolardosesof urn
awotbatsasecrahvneeaddlycazetel2lds.(cid:1)aAnMfdtebarats6aedh1-oo(cid:1)nfiMnthcleuebvmaeatlinwouniat,hlthdtheetetehmcitmoioreneroosesfantlshitetoiflvxeuicoGitryEesNwceainosst i1t9s8c5lo).seandhighlytoxicrelativemethylmercury(Magosetal., bals.org/
Plus Multi-Detection Microplate Reader with Enhanced Fluores- However, little is known about acute reactions of various y g
u
cence. The lower limit did not change after 24 h of incubation. typesofhumancellsfollowingshort-timeexposuretothimer- es
Cortical neurons demonstrated higher sensitivity to thimerosal osal in micro- and nanomolar concentrations. t on
O
comparedtofibroblasts.Thefirstsignoftoxicitywasanincrease In this paper we used a convenient and easily reproducible c
to
in membrane permeability to DAPI afte r 2 h ofincubation with combinationoffluorescenttechniquesanalyzingvariousmark- b
e
250(cid:1)Mthimerosal.A6-hincubationresultedinfailuretoexclude ers of DNA and membrane damage, and investigated the r 1
DAPI, generation of DNA breaks, caspase-3 activation, and de- toxicity of micromolar and nanomolar concentrations of , 20
1
velopment of morphological signs of apoptosis. We demonstrate thimerosal (125 nM–250 (cid:1)M) occurring in the first 24 h of 6
that thimerosal in micromolar concentrations rapidly induce
exposure in cultures of human cortical neuronal cells and in
membrane and DNA damage and initiate caspase-3–dependent
human fibroblasts.
apoptosis in human neurons and fibroblasts. We conclude that a
Wefoundthatthimerosalinmicromolarconcentrationsrap-
proposed combination of fluorescent techniques can be useful in
idlydecreasedcellularviability.Withinseveralhafterthimer-
analyzingthetoxicityofthimerosal.
Key Words: thimerosal; active caspase-3; apoptosis; toxicity; osal administration, cells lost their capability to exclude the
neurons;fibroblasts;DNAbreaks;membranedamage;DAPI. fluorescent dye 4(cid:1),6-diamidino-2-phenylindole dihydrochlo-
ride(DAPI)anddevelopedmultipleDNAbreaksaccompanied
by caspase-3 activation and apoptotic morphology. Neuronal
cell cultures demonstrated a higher sensitivity to thimerosal
Thimerosal (sodium ethylmercury-thiosalicylate) is an anti-
compared with fibroblasts.
bacterialandantifungalmercurialcompoundusedasapreser-
vative in biological products and vaccines, in concentrations
MATERIALS AND METHODS
1To whom correspondence should be addressed. Fax: [phone].
Cell cultures. HCN-1A Human cerebral cortical neurons (CRL-10442)
E-mail:[email protected].
were purchased from American Type Culture Collection (ATCC, Manassas,
ToxicologicalSciences74(2),©SocietyofToxicology2003;allrightsreserved. VA)andwereculturedaccordingtoATCCrecommendations.Thelinewas
361